Phenyl Chloro(thionoformate): a New Dealkylating Agent of Tertiary Amines

Millan, David S.; Prager, R. H.

doi:10.1071/ch98147

Cited by 11 publications

(6 citation statements)

References 16 publications

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“…The literature indicates that benzoyl chloride is more reactive toward methanol than is thiobenzoyl chloride . In this connection, the reactions of phenoxycarbonyl chloride and phenoxythiocarbonyl chloride with secondary alcohols in the presence of Et 3 N has been examined and, whereas the carbonyl chloride reacts normally to give the expected ester (eq ), the thiocarbonyl chloride reaction occurs by nucleophilic substitution at an ethyl group on N, leading to a thioamide as the product (eq ) . It might be noted that the thioester is formed when a pyridine base is used and dealkylation is not possible.…”

Section: Resultsmentioning

confidence: 99%

Disparate Behavior of Carbonyl and Thiocarbonyl Compounds: Acyl Chlorides vs Thiocarbonyl Chlorides and Isocyanates vs Isothiocyanates

Wiberg¹,

Wang²,

Miller³

et al. 2009

J. Org. Chem.

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The reaction of benzoyl chloride with methanol catalyzed by pyridine is 9 times more rapid than is the same reaction with thiobenzoyl chloride. The difference in reactivity, as well as the dealkylation reactions that occur when the reaction of thiobenzoyl chloride is catalyzed by bases such as Et 3 N, can be understood in terms of the charge distributions in the intermediate acylammonium ions. The reaction of PhNCO with ethanol occurs at a much higher rate (4.8 × 10 4 ) than that of PhNCS, corresponding to a difference in activation free energies for the additions of 6 kcal/mol. Transition states for each of these reactions were located, and each involves two alcohol molecules in a hydrogen

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Section: Resultsmentioning

confidence: 99%

Disparate Behavior of Carbonyl and Thiocarbonyl Compounds: Acyl Chlorides vs Thiocarbonyl Chlorides and Isocyanates vs Isothiocyanates

Wiberg¹,

Wang²,

Miller³

et al. 2009

J. Org. Chem.

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“…Notably, as shown in eq 1, when reactions are conducted with DMAP in the presence of Et 3 N, thiocarbonate 8 is not formed. Rather, the addition product 9 , derived from triethylamine addition to phenyl chlorothionoformate followed by dealkylation, is formed preferably as the major product (eq 1) . On the other hand, thiocarbonate 8 is readily obtained when the reaction is performed with a variety of pyridines, suggesting that a general base mechanism may result in efficient reactions at room temperature (eq 2).…”

Section: Resultsmentioning

confidence: 99%

Site-Selective Catalysis of Phenyl Thionoformate Transfer as a Tool for Regioselective Deoxygenation of Polyols

et al. 2008

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We report the application of peptide-embedded imidazoles as catalysts for the site-selective delivery of the phenyl thionoformate unit as a prelude to deoxygenation reactions of polyols. Methodology was developed that allows for the synthesis of thiocarbonyl derivatives based on a combination of additives that include N-alkylimidazoles and FeCl 3 as co-catalysts. The use of this reagent combination leads to increased reaction rates and efficient yields relative to simple basemediated reactions. In terms of controlling regioselectivity during the course of polyol modification, we found that histidine-containing peptides, in combination with FeCl 3 , could lead to modulation of the product distribution. Through screening of peptides and control of reaction conditions, products could be observed that reflected both the inherent preference of substrates, and also reversal of inherent selectivity.

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“…Procedure D was followed with the only exception that Et 3 N (dealkylating procedure of Millan and Prager) has been used instead of N -methylaniline.…”

Section: Methodsmentioning

confidence: 99%

Radical O→C Transposition: A Metal-Free Process for Conversion of Phenols into Benzoates and Benzamides

et al. 2011

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We report a metal-free procedure for transformation of phenols into esters and amides of benzoic acids via a new radical cascade. Diaryl thiocarbonates and thiocarbamates, available in a single high-yielding step from phenols, selectively add silyl radicals at the sulfur atom of the C═S moiety. This addition step, analogous to the first step of the Barton-McCombie reaction, produces a carbon radical which undergoes 1,2 O→C transposition through an O-neophyl rearrangement. The usually unfavorable equilibrium in the reversible rearrangement step is shifted forward via a highly exothermic C-S bond scission in the O-centered radical, which furnishes the final benzoic ester or benzamide product. The metal-free preparation of benzoic acid derivatives from phenols provides a potentially useful alternative to metal-catalyzed carbonylation of aryl triflates.

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Phenyl Chloro(thionoformate): a New Dealkylating Agent of Tertiary Amines

Cited by 11 publications

References 16 publications

Disparate Behavior of Carbonyl and Thiocarbonyl Compounds: Acyl Chlorides vs Thiocarbonyl Chlorides and Isocyanates vs Isothiocyanates

Disparate Behavior of Carbonyl and Thiocarbonyl Compounds: Acyl Chlorides vs Thiocarbonyl Chlorides and Isocyanates vs Isothiocyanates

Site-Selective Catalysis of Phenyl Thionoformate Transfer as a Tool for Regioselective Deoxygenation of Polyols

Radical O→C Transposition: A Metal-Free Process for Conversion of Phenols into Benzoates and Benzamides

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